《植物生理学报》 2016, 52(10): 1527-1536

不同叶色型苋菜叶片光合生理特性对弱光胁迫及恢复的响应

欧宇丹, 邵玲^*, 周澄, 杨婷娟, 赵鑫

肇庆学院生命科学学院, 广东肇庆526061

通信作者：邵；E-mail: shaoling@zqu.edu.cn

摘　要：

采用人工设施遮阴大棚, 分析两种不同叶色型苋菜对弱光胁迫及其恢复生长的光合生理特性异同, 揭示和比较2种叶色型苋菜对弱光的调节机制。结果表明: 15 d弱光处理显著抑制了‘绿叶苋’和‘花红苋’的形态建成, 叶面积最大降幅分别为46.0%与33.9%, 叶片组织结构发育较差, 叶绿体排列疏松, 体积变大。‘花红苋’叶片下表皮细胞的红色素积累显著减少, 弱光15 d时苋菜红素含量仅为处理前的28.9%, 但叶绿素含量增加明显(P<0.01)。弱光不同程度提高了两种苋菜叶中叶绿素和类胡萝卜素的含量, ‘绿叶苋’ Chl a/Chl b比值的降幅显著大于‘花红苋’ (P<0.01)。弱光下, 两种苋菜的净光合速率(P_n)、蒸腾速率(T_r)和气孔导度(G_s)显著下降, 胞间CO₂浓度(C_i)明显升高。弱光胁迫期‘绿叶苋’的光饱和点约为800 μmol•m^-2•s^-1, 高出‘花红苋’的1/3左右, 在持续的高光照量(800~1 800 μmol•m^-2•s^-1)范围内, ‘花红苋’则表现出明显的光抑制效应。当解除弱光胁迫恢复自然光照仅3 d, ‘绿叶苋’的P_n和G_s优于‘花红苋’ 10%~20%。可见, ‘花红苋’品种的耐阴性优于‘绿叶苋’, 弱光环境下苋菜红素含量的下调可能是维持叶片光合生理稳定性的因素之一。

关键词：苋菜; 弱光胁迫; 光合生理; 叶色型; 恢复生长

收稿：2016-07-19   修定：2016-08-30

资助：广东省大学生科技创新培育专项(pdjh2016a0536)、国家自然科学基金(31201142)、广东省大学生创新训练计划(201610580013)、广东省教育厅创新团队项目(2015KCXTD032)和肇庆学院实践教学改革研究项目(sjjx201518)。 致谢 肇庆学院第二批创新科研团队(肇学院[2016]48号)提供科研条件支持; 生命科学学院李诗婷、张定、谭佩婷和陈甜妹同学参与研究工作。

The response of photosynthetic physiological characteristics in leaves of different leaf-color types of Amaranthus tricolor under weak light stress and its recovery

OU Yu-Dan, SHAO Ling^*, ZHOU Cheng, YANG Ting-Juan, ZHAO Xin

College of Life Sciences, Zhaoqing University, Zhaoqing, Guangdong 526061, China

Corresponding author: SHAO Ling; E-mail: shaoling@zqu.edu.cn

Abstract:

In order to reveal the adjustment mechanism of light-loving C₄ species—Amaranthus tricolor to weak light, the artificial facilities of shading sheds were used in the present study and the responses of photosynthetic physiological traits in two diverse leaf-color types of A. tricolor during the weak light stress and subsequent recovery periods were investigated. The results showed as follows: 15 d-treatment of weak light stress significantly inhibited the morphogenesis of ‘Red flower’ type and ‘Green leaf’ type of A. tricolor, the largest reduction of leaf area was 46.0% and 33.9%, respectively; the leaf tissue was bad-developed, chloroplast loosely arranged and the volume of chloroplast enlarged. The accumulation of red pigments in the leaf epidermal cells of ‘Red flower’ type decreased significantly, and the amaranthine content was only 28.9% of the pretreatment level after 15 d of weak light stress treatment, but the contents of chlorophyll increased (P<0.01). Weak light to different degrees improved the contents of chlorophyll and carotenoids in the leaves of two leaf-color types of A. tricolor, the decreasing amplitude of Chl a/b ratio was significantly higher in the ‘Green leaf’ type than in the ‘Red flower’ one (P<0.01). Under weak light conditions, net photosynthetic rate (P_n), transpiration rate (T_r) and stomatal conductance (G_s) decreased significantly while intercellular CO₂ concentration (C_i) obviously increased in two types of A. tricolor. During the period of weak light stress treatment, the light saturation point of ‘Green leaf’ type was approximately 800 μmol•m^-2•s^-1, 1/3 higher than that of ‘Red flower’ one, and moreover, ‘Red flower’ one exhibited an obvious photoinhibitory effect within the range of high-intensity light (800–1 800 μmol•m^-2•s^-1). After only 3 d re-illumination of natural light, the values of P_n and G_s of ‘Green leaf’ type were 10%–20% higher than those of ‘Red flower’ one. This showed that ‘Red flower’ type have better shade tolerance than the ‘Green leaf’ one, and the down-regulated of amaranthine content in the ‘Red flower’ type may be one of the maintain the stability of the photosynthetic physiological factor.

Key words: Amaranthus tricolor; weak light stress; photosynthetic physiology; leaf-color types; recovering growth